The invention relates to a transmission, specifically a speed-changing gear transmission, with at least an input shaft and an output shaft and in some cases a countershaft, with a plurality of gear pairs comprising free gears that can be brought to a rotation-locked engagement with a first shaft by means of clutches and fixed gears that are permanently rotation-locked to a second shaft, and with a start-up clutch arranged at the input side of the transmission to couple and uncouple the flow of torque.
Transmissions of this kind are generally known in the field of motor vehicles. They suffer from the drawback that they cannot be shifted under load. In other words, vehicle traction is interrupted every time the transmission is shifted to change gear ratios.
It is therefore the object of the present invention to provide a transmission according to the foregoing general description which can be shifted under load and at the same time has an uncomplicated design with regard to its constituent elements.
To meet the foregoing objective, the invention introduces the concept that at least one of the clutches is designed as a high-torque clutch, such as a power-shift clutch, and that the start-up clutch and the power-shift clutch can be actuated by at least one actuator unit.
In this arrangement, it can be of practical advantage if it is possible to engage the power-shift clutch while the start-up clutch is at least partially engaged.
Likewise, it is useful if it is possible to engage the power-shift clutch at a time when the start-up clutch is already engaged. The term xe2x80x9cto engagexe2x80x9d in this context means to increase the amount of torque that can be transmitted by the clutch.
It is advantageous, if at least one free gear can be connected to a shaft by means of a first clutch and/or a power-shift clutch.
It is further useful if two of the free gears can be connected to a shaft by means of a first clutch and/or a power-shift clutch.
It is likewise practically suitable if the free gear of the highest gear-ratio of the transmission can be connected to a shaft by means of a clutch and/or a power-shift clutch.
In a further embodiment, it is also of practical benefit if the clutch by which at least one free gear is coupled to a shaft is a form-locking clutch.
It is also suitable if the clutch by which at least one free gear is coupled to a shaft is a friction clutch.
It is further beneficial if the clutch by which at least one free gear is coupled to a shaft has an interposed synchronizer device.
It is also practical, it the power-shift clutch is a friction clutch. In, particular, it is practically suitable if the start-up clutch is a friction clutch.
It is advantageous if the start-up clutch is arranged in a space within a bell housing.
It also practically suitable if at least one power-shift clutch is arranged in a space within a bell housing.
It is further practical if the start-up clutch and at least one power-shift clutch are dry-friction clutches.
It is likewise of practical benefit if the start-up clutch is arranged inside the transmission housing.
Also practical is an arrangement where at least the power-shift clutch is inside the transmission housing.
It is also advantageous if the start-up clutch and/or at least one power-shift clutch is a friction clutch.
It is further advantageous if the start-up clutch is a hydrodynamic torque converter with or without a converter-lockup clutch.
In another embodiment, it is practical if the actuator for the start-up clutch and at least one power-shift clutch is energized by a pressure medium and has a pressure-medium supply and at least one valve controlling the supply of pressure medium to the slave cylinders, each of the two clutches being equipped with one slave cylinder.
According to a further concept of the invention, it is practical if the actuator for the start-up clutch and at least one power-shift clutch is electro-mechanically driven, with the possibility of arranging a speed-magnifying or speed-reducing gear box in series after an electric motor or electric magnet.
In accordance with a further concept of the present invention, it is practical if the actuator of the clutches that are used for gear-shifting is a pressure-powered actuator with a pressure-medium supply and at least one valve controlling the supply of pressure medium to the slave cylinders, each of the clutches being equipped with one slave cylinder.
According to another concept of the invention, it is practical if the actuator of the clutches that are used for gear-shifting is electro-mechanically driven, with the possibility of arranging a speed-magnifying or speed-reducing gear box in series after an electric motor or electric magnet.
In accordance with a further concept of the invention, it is practical if the transmission comprises an electro-mechanical energy converter serving as starting motor of the engine of the vehicle and/or as generator serving to produce and recuperate electrical energy from kinetic energy.
It is advantageous if the electromechanical energy converter drives or can be driven by way of a fixed gear of the transmission.
In accordance with a further concept of the invention, it is advantageous if the electromechanical energy converter drives or can be driven by the engine of the vehicle by way of a flywheel.
Under a further concept according to the invention, it is practical if the electromechanical energy converter drives or can be driven by way of the input shaft of the transmission.
It is practical for the electromechanical energy converter to have a stator and a rotor in coaxial alignment with the transmission input shaft.
It is practical for the electromechanical energy converter to have a stator and a rotor that are aligned in relation to an axis which runs essentially parallel to the transmission input shaft.
It is further practical for the electromechanical energy converter to have a stator and a rotor that are aligned coaxially to the transmission input shaft in an arrangement where the rotor has a rotation-locked connection with a flywheel or with an element that is connected to the transmission input shaft.
The novel features that are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing.